Arc Welding Robots
  In general, equipment for automatic arc welding is designed differently from that used for manual arc welding. Automatic arc welding normally involves high duty cycles, and the welding equipment must be able to operate under those conditions. In addition, the equipment components must have the necessary features and controls to interface with the main control system. A special kind of electrical power is required to make an arc weld, the special power is provided by a welding machine also known as a power source. All arc-welding processes use an arc welding gun or torch to transmit welding current from a welding cable to the electrode. They also provide for shielding the weld area from the atmosphere. The nozzle of the torch is close to the arc and will gradually pick up spatter. A torch cleaner (normally automatic) is often used in robot arc welding systems to remove the spatter. All of the continuous electrode wire arc processes require an electrode feeder to feed the consumable electrode wire into the arc. Welding fixtures and work piece manipulators hold and position parts to ensure precise welding by the robot.

The productivity of the robot-welding cell is speeded up by having an automatically rotating or switching fixture, so that the operator can be fixing one set of parts while the robot is welding another. To be able to guarantee that the electrode tip and the tool frame are accurately known with respect to each other, the calibration process of the TCP (Tool Center Point) is important. An automatic TCP calibration device facilitates this time consuming task.

For welding it has almost entirely replaced the other types except for the Cartesian, which is used for very large and very small robots. The reason for the popularity of the jointed arm type is that it allows the welding torch to be manipulated in almost the same fashion as a human being would manipulate it. The torch angle and travel angle can be changed to make good quality welds in all positions. Jointed arm robots also allow the arc to weld in areas that are difficult to reach. Even so, a robot cannot provide the same manipulative motion as a human being, although it can come extremely close. In addition, jointed arm robots are the most compact and provide the largest work envelope relative to their size. Usually arc-welding robots have five or six free programmable arms or axes; Allowing the robot to perform better and more accurately.
  FANUC America